The SH-2 was designed in response to a 1956 US Navy competition for a new multipurpose helicopter. Kaman's design, known to the company as the K-20 won, and four YHU2K-1 prototypes were built. The aircraft first flew on July 2nd, 1959, and entered service in December, 1962. It was redesignated UH-2 under the new tri-service designation system in 1962. The first production version was the HU2K-1 (later UH-2A), 84 examples being built with the T58-GE-8 engine delivering 1,250 shp (932 kW).